Postcoital contraceptive

In 1973, the FDA considered DES safe as ‘morning-after’ pill

1983 Study Abstract

Postcoital contraceptives, the so-called “morning after pill,” are agents used as emergency treatment to prevent pregnancy after unprotected intercourse or contraceptive accidents.

In the 1960s and early 1970s high doses of estrogens were used in 5-day courses such as diethylstilbestrol 25-50 mg a day or ethinyl estradiol 0.5-5 mg a day begun within 72 hours after coitus. Although effective, a considerable drawback of the associated nausea and vomiting as well as an increased risk of menstrual disturbance during the treatment cycle.

Norgestrel alone in various dosages has been used postcoitally.

Quingestanol has been used as a continuing postcoital agent in Latin America but proved unacceptable owing to nausea and irregular bleeding.

In China “visiting pills” have been devised containing anordrin. In the West regimens of this sort have been superseded by the Yuzpe treatment of 100 mcg ethinylestradiol and 0.5 mg levonorgestrel initially, repeated after precisely 12 hours. The treatment must be initiated within 72 hours of exposure.

Postcoital contraceptives act by combinations of mechanisms–the function of the corpus luteum is disrupted, tubal motility may be affected, and changes in endometrial biochemistry prevent ovoimplantation. In a multicenter trial involving 602 women Yuzpe reported a pregnancy rate of 1.6%. Other workers show comparable figures of 0-3%. The primary side effects of the current hormonal method are nausea, which occurs in 61% of cases, and vomiting, 20% of cases. Both are mild and of short duration.

All postcoital methods carry a risk of ectopic pregnancy should the treatment fail. 3 ectopic pregnancies were recorded with diethylstilbestrol and 1 recently with the Yuzpe regimen. There have been no reports of thromboembolic complications.

If a hormonal form of postcoital treatment fails, the theoretical possibility of the pregnancy being harmed cannot be ruled out. The patient needs to be counseled about this, and careful records should be kept. Also important is the taking of an accurate menstrual and coital history to exclude exposures earlier in the menstrual cycle.

Lippes and coworkers showed the efficacy of copper IUDs as postcoital agents. These can be used up to 5 days from intercourse. An IUD is preferred if hormones are contraindictated, if exposure was more than 72 hours beforehand, if the woman desires the most effective method, and if she wants the IUD for longterm contraception.

Postcoital contraception, however defined, raises ethical questions. Postcoital methods could be classed as contraceptive rather than abortive within the maximum period (defined by medical scientific consensus) that may elapse between intercourse and nidation.

Sources

DES DIETHYLSTILBESTROL RESOURCES

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